ISO 3384-2:2019
(Main)Rubber, vulcanized or thermoplastic — Determination of stress relaxation in compression — Part 2: Testing with temperature cycling
Rubber, vulcanized or thermoplastic — Determination of stress relaxation in compression — Part 2: Testing with temperature cycling
This document specifies two methods for determining the decrease in counterforce exerted by a test piece of vulcanized or thermoplastic rubber which has been compressed to a constant deformation and then undergoes temperature cycling. Method A: The temperature is cycled at intervals between a high temperature for ageing and a low temperature for checking the sealing force at this low temperature. Method B: The temperature is cycled continuously between a high temperature and a low temperature to introduce thermal stress in the test piece. The counterforce is determined by means of a continuous-measurement system. Two forms of test pieces are specified in this document: cylindrical test pieces and rings. Comparison of results is valid only when made on test pieces of similar size and shape. The use of ring test pieces is particularly suitable for the determination of stress relaxation in liquid environments.
Caoutchouc vulcanisé ou thermoplastique — Détermination de la relaxation de contrainte en compression — Partie 2: Essais avec cycles de température
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INTERNATIONAL ISO
STANDARD 3384-2
Second edition
2019-08
Rubber, vulcanized or
thermoplastic — Determination of
stress relaxation in compression —
Part 2:
Testing with temperature cycling
Caoutchouc vulcanisé ou thermoplastique — Détermination de la
relaxation de contrainte en compression —
Partie 2: Essais avec cycles de température
Reference number
©
ISO 2019
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus . 2
6 Calibration . 3
7 Test piece . 3
7.1 Type and preparation of test pieces . 3
7.1.1 General. 3
7.1.2 Cylindrical test pieces . 3
7.1.3 Ring test pieces. 4
7.2 Measurement of dimensions of test pieces . 4
7.3 Number of test pieces . 4
7.4 Time interval between forming and testing . 4
7.5 Conditioning of test pieces . 4
8 Duration, temperature and test liquid . 5
8.1 Duration of test . 5
8.2 Temperature of exposure . 5
8.3 Immersion liquids . 5
9 Procedure. 5
9.1 Preparation . 5
9.2 Thickness measurement . 5
9.2.1 Cylindrical test pieces . 5
9.2.2 Ring test pieces. 5
9.3 Method A . 6
9.4 Method B . 7
10 Expression of results . 8
11 Precision . 9
12 Test report . 9
Annex A (normative) Calibration schedule .11
Bibliography .14
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 45, Rubber and rubber products,
Subcommittee SC 2, Testing and analysis.
This second edition cancels and replaces the first edition (ISO 3384-2:2012), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— the requirement for compression device (5.1) has been harmonized with other International
Standards;
— other changes have been made to keep the consistency with ISO 3384-1 throughout the document.
A list of all parts in the ISO 3384 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2019 – All rights reserved
Introduction
When a constant strain is applied to rubber, the force necessary to maintain that strain is not constant
but decreases with time; this behaviour is called “stress relaxation”. Conversely, when rubber is
subjected to a constant stress, an increase in the deformation takes place with time; this behaviour is
called “creep”.
Tests in compression are normally made under continuous stress conditions (i.e. the test piece remains
strained throughout the test), and are hence a measure of sealing force. Note that the terms continuous
and discontinuous used in this standard refer to whether the measure of force is made continuously of
at intervals.
Tests to use stress relaxation in tension as a measure of ageing are given in ISO 6914.
The processes responsible for stress relaxation can be physical or chemical in nature, and under
all normal conditions both types of process will occur simultaneously. However, at normal or low
temperatures and/or short times, stress relaxation is dominated by physical processes, while at high
temperatures and/or long times chemical processes are dominant.
If the life-time of a material is to be investigated, it can be determined using the method described in
ISO 11346.
In addition to the need to specify the temperatures and time intervals in a stress relaxation test, it is
necessary to specify the initial stress and the previous mechanical history of the test piece since these
can also influence the measured stress relaxation, particularly in rubbers containing fillers.
The most important factor in achieving good repeatability and reproducibility when making stress
relaxation tests is to keep the compression constant during all measurements.
The two cycling test methods specified are designed to carry out the following:
— age the test piece by stress relaxation and determine the sealing force at low temperatures
(method A);
— introduce thermal stress by stress relaxation and determine the sealing force at low temperatures
(method B).
For products used in outdoor applications where the temperature can cycle between a low temperature
(e.g. −40 °C) and a high temperature (e.g. 150 °C), it is important to also consider the shrinking of the
rubber at low temperatures when assessing performance in the anticipated application and life-time.
For polymers that crystallize at low temperature, the crystallization will add to the shrinking of
the rubber. For example, for hoses and seals in automotive applications, the product might work
satisfactorily at the normal working temperature, but might leak at a low temperature.
INTERNATIONAL STANDARD ISO 3384-2:2019(E)
Rubber, vulcanized or thermoplastic — Determination of
stress relaxation in compression —
Part 2:
Testing with temperature cycling
WARNING 1 — Persons using this document should be familiar with normal laboratory practice.
This document does not purport to address all of the safety problems, if any, associated with its
use. It is the responsibility of the user to establish appropriate safety and health practices and to
determine the applicability of any other restrictions.
WARNING 2 — Certain procedures specified in this document might involve the use or generation
of substances, or the generation of waste, that could constitute a local environmental hazard.
Reference should be made to appropriate documentation on safe handling and disposal after use.
1 Scope
This document specifies two methods for determining the decrease in counterforce exerted by a test
piece of vulcanized or thermoplastic rubber which has been compressed to a constant deformation and
then undergoes temperature cycling.
Method A: The temperature is cycled at intervals between a high temperature for ageing and a low
temperature for checking the sealing force at this low temperature.
Method B: The temperature is cycled continuously between a high temperature and a low temperature
to introduce thermal
...
INTERNATIONAL ISO
STANDARD 3384-2
Second edition
2019-08
Rubber, vulcanized or
thermoplastic — Determination of
stress relaxation in compression —
Part 2:
Testing with temperature cycling
Caoutchouc vulcanisé ou thermoplastique — Détermination de la
relaxation de contrainte en compression —
Partie 2: Essais avec cycles de température
Reference number
©
ISO 2019
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus . 2
6 Calibration . 3
7 Test piece . 3
7.1 Type and preparation of test pieces . 3
7.1.1 General. 3
7.1.2 Cylindrical test pieces . 3
7.1.3 Ring test pieces. 4
7.2 Measurement of dimensions of test pieces . 4
7.3 Number of test pieces . 4
7.4 Time interval between forming and testing . 4
7.5 Conditioning of test pieces . 4
8 Duration, temperature and test liquid . 5
8.1 Duration of test . 5
8.2 Temperature of exposure . 5
8.3 Immersion liquids . 5
9 Procedure. 5
9.1 Preparation . 5
9.2 Thickness measurement . 5
9.2.1 Cylindrical test pieces . 5
9.2.2 Ring test pieces. 5
9.3 Method A . 6
9.4 Method B . 7
10 Expression of results . 8
11 Precision . 9
12 Test report . 9
Annex A (normative) Calibration schedule .11
Bibliography .14
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 45, Rubber and rubber products,
Subcommittee SC 2, Testing and analysis.
This second edition cancels and replaces the first edition (ISO 3384-2:2012), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— the requirement for compression device (5.1) has been harmonized with other International
Standards;
— other changes have been made to keep the consistency with ISO 3384-1 throughout the document.
A list of all parts in the ISO 3384 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2019 – All rights reserved
Introduction
When a constant strain is applied to rubber, the force necessary to maintain that strain is not constant
but decreases with time; this behaviour is called “stress relaxation”. Conversely, when rubber is
subjected to a constant stress, an increase in the deformation takes place with time; this behaviour is
called “creep”.
Tests in compression are normally made under continuous stress conditions (i.e. the test piece remains
strained throughout the test), and are hence a measure of sealing force. Note that the terms continuous
and discontinuous used in this standard refer to whether the measure of force is made continuously of
at intervals.
Tests to use stress relaxation in tension as a measure of ageing are given in ISO 6914.
The processes responsible for stress relaxation can be physical or chemical in nature, and under
all normal conditions both types of process will occur simultaneously. However, at normal or low
temperatures and/or short times, stress relaxation is dominated by physical processes, while at high
temperatures and/or long times chemical processes are dominant.
If the life-time of a material is to be investigated, it can be determined using the method described in
ISO 11346.
In addition to the need to specify the temperatures and time intervals in a stress relaxation test, it is
necessary to specify the initial stress and the previous mechanical history of the test piece since these
can also influence the measured stress relaxation, particularly in rubbers containing fillers.
The most important factor in achieving good repeatability and reproducibility when making stress
relaxation tests is to keep the compression constant during all measurements.
The two cycling test methods specified are designed to carry out the following:
— age the test piece by stress relaxation and determine the sealing force at low temperatures
(method A);
— introduce thermal stress by stress relaxation and determine the sealing force at low temperatures
(method B).
For products used in outdoor applications where the temperature can cycle between a low temperature
(e.g. −40 °C) and a high temperature (e.g. 150 °C), it is important to also consider the shrinking of the
rubber at low temperatures when assessing performance in the anticipated application and life-time.
For polymers that crystallize at low temperature, the crystallization will add to the shrinking of
the rubber. For example, for hoses and seals in automotive applications, the product might work
satisfactorily at the normal working temperature, but might leak at a low temperature.
INTERNATIONAL STANDARD ISO 3384-2:2019(E)
Rubber, vulcanized or thermoplastic — Determination of
stress relaxation in compression —
Part 2:
Testing with temperature cycling
WARNING 1 — Persons using this document should be familiar with normal laboratory practice.
This document does not purport to address all of the safety problems, if any, associated with its
use. It is the responsibility of the user to establish appropriate safety and health practices and to
determine the applicability of any other restrictions.
WARNING 2 — Certain procedures specified in this document might involve the use or generation
of substances, or the generation of waste, that could constitute a local environmental hazard.
Reference should be made to appropriate documentation on safe handling and disposal after use.
1 Scope
This document specifies two methods for determining the decrease in counterforce exerted by a test
piece of vulcanized or thermoplastic rubber which has been compressed to a constant deformation and
then undergoes temperature cycling.
Method A: The temperature is cycled at intervals between a high temperature for ageing and a low
temperature for checking the sealing force at this low temperature.
Method B: The temperature is cycled continuously between a high temperature and a low temperature
to introduce thermal
...
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